Arm A: Metformin plus rosiglitazone placebo. Arm B: Metformin placebo plus rosiglitazone. Arm C: Metformin plus rosiglitazone. Arm D: Metformin placebo plus rosiglitazone placebo. Patients who are still on study drugs at Week 16 (at either full or reduced dose) are switched to the open-label phase to receive the combination of metformin and rosiglitazone through Week 32. Patients have evaluations at Weeks 2, 4, 8, 12, 16, 18, 20, 24, 28, and 32. [AS PER AMENDMENT 02/05/02: Evaluations must be performed under fasting conditions.] Safety indices, fasting insulin and glucose levels, visceral [AS PER AMENDMENT 02/05/02: and subcutaneous abdominal] fat are assessed. [AS PER AMENDMENT 02/05/02: Patients who discontinue study treatment due to pregnancy during the study will have the Week 32 evaluations (except CT and DEXA scans).] [AS PER AMENDMENT 02/05/02: A mid-thigh measurement was added to the study as a secondary endpoint to look for changes in extremity subcutaneous fat from therapy with rosiglitazone. Rosiglitazone and other peroxisome proliferator-activated receptor (PPAR) gamma activators increase subcutaneous adipogenesis and may thus increase subcutaneous fat and improve insulin resistance in this way.]